Upgrade ferdi-beta to 5.6.0-beta.8 (#11419)
Upgrade ferdi-beta to 5.6.0-beta.8 (#11419)

* Upgrade ferdi-beta to 5.6.0-beta.8

* add livecheck, remove appcast

Co-authored-by: Bevan Kay <a88b7dcd1a9e3e17770bbaa6d7515b31a2d7e85d@bevankay.me>
404NetworkError/homebrew-versions,404NetworkError/homebrew-versions,mahori/homebrew-cask-versions